“Three percent – that’s the highest in Wyoming, and actually, that’s almost the highest in the nation,” Liu said. “The main reason is that Natrona County, and particularly Casper, is a service center in the region.”

Liu says mineral extraction is still fueling the state’s growth. He says a lack of mineral extraction in some counties led to some regional population decreases, however.

“About five counties slightly lost population, and, traditionally, these small and rural counties without much mineral extraction have very slow population increases, so they may lose people,” Liu said.

Weston County, Niobrara County, Carbon County, Washakie County and Lincoln County had estimated population declines last year. At 1.3 percent, Niobrara County had the steepest population decline.